The FDNY is trying to ax a black firefighter — who allegedly tested positive for marijuana — before he can retire on a three-quarters disability pension.

If he wins, firefighter Kevin Simpkins, who made $97,500 in 2013, would receive a lifelong, tax-free pension of 75 percent of his last 12 months’ pay.

If fired, he would get 50 percent, and the payments would not start until 2023.

In a racially charged administrative trial, Simpkins, 46, denied using pot. He contends the FDNY targeted him in retaliation for his involvement with the Vulcan Society, a fraternity of black firefighters. He was one of seven named plaintiffs in the Vulcans’ 2007 discrimination lawsuit, which the city settled in March for $98 million — mostly in back pay for blacks passed over by the FDNY. Simpkins, who was already hired, will get less than $10,000, said his lawyer, Peter Gleason.

“The FDNY is using random drug testing to go ­after ‘enemies of the state,’ ” Gleason argued at Simpkins’ hearing.

Simpkins, who joined the FDNY 11 years ago after serving in the Navy and at other jobs, testified that he was ostracized and taunted by fellow Bravest at Engine 233 in Brooklyn. “I was called a ­n—-r, a lowlife, a chimp,” he said, adding: “The treatment I received escalated because I was a Vulcan member.”

Last September, Simpkins, along with three white firefighters and their commanding officer on a night shift, was picked for urine testing.

The FDNY said Simpkins had traces of marijuana. Gleason is challenging the results. Pending his trial, the FDNY assigned Simpkins to its audio-visual unit in Brooklyn.

Last Nov. 1, Simpkins was driving back after an assignment when he collided with a car that entered the intersection against a red light. Lab tests on Simpkins showed no sign of drugs.

He underwent surgery for a torn rotator cuff and filed an application in March to retire on disability.